Effect Of Fluid On Stability Of Sieve Tray Structure

Sieve column is widely used in chemical production because of its simplestructure, which makes it not only easy to manufacture and maintenance, but alsoconvenient for theoretical description and experimental research. However, withlarge-scalization and long operating cycle of petro chemical equipments, severalfailures as plate tilt or collapse are often found during overhaul period. This is mainlydue to the fluid flowing in the column, and further research becomes very necessary.The effect of superficial gas velocity, liquid flow and the height of weir on thevibration of a sieve tray column have been experimentally studied using a600mmdiameter plexiglass column with air-water system. Air and water interacted by theway of cross flow, and the contacting regime was mixed froth which occurs mostcommonly in the atmospheric tower. The results showed that the frequency value oftray vibration increased with the rise of superficial gas velocity, while decreased withthe rise of the height of weir, and the effect of liquid flow was insensitive. Whenoperating conditions deviate from the normal range, it may cause large vibration andplastic deformation.The effect of superficial gas velocity, opening ratio and hole diameter on thestability of a sieve tray is studied by the finite-element method. The simulation resultsare compared to the experimental results and validated to be effective. On this basis,an effective model is established using ANSYS to simulate the physics process ofhigh-speed gas flowing through sieve tray, and the stress distribution under differentoperation parameters and structure parameters. Results show that stresses at the centerand edge of the tray are higher than other areas, and the stress of the tray increasedwith superficial gas velocity in a second power relation, however, sharply decreasedwith the opening ratio. There exists an optimal hole diameter which makes the stressof tray lower when the opening ratio is fixed. Based on the numerical modelmentioned above, for the first time, a simplified model is established to simulate thephysics process of normal operation conditions.The results in this paper provide some references for the design of sieve tray, theimprovement of the working environment and process efficiency.